MOOP!

How many relationships does someone have to go through before they're expected to have a pretty good idea of what rules they have? Should you just count ended relationships? How badly does poly confuse the issue?

There's no fixed number. As for "expected to", people have pretty much come to understand that nobody is "expected to" have a good idea of what rules they have. It's more like a person has a set of rules, another person has a different set of rules, and the relationship between the two has its own set of rules. The rules that are applied to the relationship generally approximate a union of these three sets.

Counterintuitively, poly does not confuse the issue, but, by providing comparisons and multiple points of view*, clarifies it.

* Better yet, when you wish to analyze one relationship, and can't do so with its participants, you can often go to your other sweeties and ask for their input. This, to me, is one of the wonderful things about poly.